1. Field of the Invention
The present invention relates to the field of telecommunications. More particularly, the present invention relates to area wide central exchange service (centrex) and private branch exchange (PBX) systems.
2. Acronyms
The written description provided herein contains acronyms that refer to various telecommunications services, components and techniques, as well as features relating to the present invention. Although some of these acronyms are known, use of these acronyms is not strictly standardized in the art. For purposes of the written description herein, the acronyms are defined as follows:    Access Code (AC)    Advanced Intelligent Network (AIN)    American Standard Code for Information Interchange (ASCII)    Automatic Selection of Facilities-Remote Tie Line (ASF-RTL)    Asynchronous Transfer Mode (ATM)    Called Party Number (CDN)    Calling Party Number (CPN)    Call Type Code (CTC)    Carrier Identification Code (CIC)    Central Exchange Service (Centrex)    Centralized Route Selection (CRS)    CentrexSMART Front End (CFE)    Custom Virtual Network (CVN)    Customized Dialing Plan-Access Code (CDP-AC)    Direct Inward Dial (DID)    Electronic Tandem Network (ETN)    File Transfer Protocol (FTP)    Initial Address Message (IAM)    Integrated Service Control Point (ISCP)    Interexchange Carrier (IXC)    Local Access and Transport Area (LATA)    Local Exchange Carrier (LEC)    Lucent Service Control Point (LSCP)    Manipulation Dialing Plan (MDP)    Multi-Frequency (MF)    Numbering Plan Area (NPA) a.k.a. area code    North American Numbering Plan (NANP)    Nature Of Number (NON)    Off Hook Delay (OHD)    Original Called Number (OCN),    Outgoing Call Screening (OCS)    Point of Presence (POP)    Private Network (PN)    Privilege Class (PC)    Private Branch Exchange (PBX)    Private Numbering Plan (RXX)    Public Office Dial Plan (PODP)    Public Switched Telephone Network (PSTN)    Redirected Number (RDN)    Regional Bell Operating Company (RBOC)    Remote Tie Line Billing Reduction (RBR)    Service Control Point (SCP)    Service Switching Point (SSP)    Signaling System 7 (SS7)    Signaling Transfer Point (STP)    Station Message Detail Recording (SMDR)    Special Dialing Plan (SDP)    Terminating Attempt Trigger (TAT)    Transaction Capabilities Application Part (TCAP)    Transmission Control Protocol/Internet Protocol (TCP/IP)    Trunk Group (TG)    Usage Billing Reduction (UBR)    Usage Billing Suppression (UBS)    Virtual Private Network (VPN)
3. Background Information
Currently, enterprises are removing private electronic tandem networks (ETNs), which are dependent on a network of private lines, in order to reduce network expenses. With the reduction in prices on public switched telephone network (PSTN) usage and the increase in price of private lines, it is desirable for enterprises to direct their call traffic over the PSTN using a local Regional Bell Operating Company (RBOC) virtual network, if available. Increased use of the PSTN also reduces responsibility for telecommunications maintenance functions within the enterprises' domain, which are inherent with any system dependent on private facilities, such as ETN and asynchronous transfer mode (ATM) facilities. Although many enterprises are comfortable sending as much traffic as possible over the PSTN, they may desire to retain portions of their private facilities, such as ATM backbones and international links, as needed, thus creating the need for a hybrid virtual private network-private network (VPN-PN).
The virtual network market is growing rapidly. Virtual network offerings by the interexchange carriers (IXCs) such as AT&T's Software Defined Network (SDN), MCI's Virtual Networking Service (VNET), and Sprint's Virtual Private Network (VPN) are the primary market players in virtual network services.
AT&T markets SDN primarily to large users and has been one of the most popular services offered by resellers and aggregators. AT&T also offers Software Defined Data Network (SDDN) as an optional feature. SDDN provides data networking capability for its SDN service. SDN provides users with on-line network management capabilities to proactively monitor and control performance, security, accounting, network planning and configuration which is a major strength. AT&T has improved its billing features by introducing OneNet, a new SDN billing service. OneNet combines the charges from a customer's SDN and 800 services onto one bill. OneNet does not, however, provide a predictable monthly bill.
MCI's VNET provides customers with long distance, voice, data and messaging services, both on domestic and international levels. VNET supports voice and data transmission up to 64 Kbps. VNET also provides optional features such as an integrated network management service. A major strength of VNET is the centralized software defined database, which can be controlled directly from a workstation on the customer's premises. MCI also offers MCI Perspective, which is a PC based software analysis tool allowing customers to track, analyze and control their telecommunications billing information. MCI Perspective does not, however, provide a predictable monthly bill.
Sprint's VPN is a voice and data network operated by a single software controlled management system through the use of shared transmission facilities. VPN supports 56 Kbps transmission and was designed for large corporate telecommunications users with multiple locations. Sprint's Insight Executive integrates the network management of VPN with other Sprint services such as 800, WATS, etc. onto a single platform. Another strength is Sprint's Insite ACT, a phone-based service change tool that allows VPN customers to add, change or cancel their VPN service.
In FLEISCHER, III et al., U.S. Pat. No. 5,974,133, the disclosure of which is expressly incorporated herein by reference in its entirety, an overlay method and system are described for a multiple location communications network, which provide additional telecommunication services, such as abbreviated dialing plans, automatic selection of routing, centralized access to private and public network facilities, and outgoing call screening. FLEISCHER, III et al.'s system is a good basic system, but provides limited flexibility and offers limited options for automatic selection of routing, centralized access to private network facilities and outgoing call screening. FLEISCHER, III et al's system also does not provide predictable periodic billing or centralized data collection.
Routing traffic to hub switches is well known in the field of telecommunications. For example, MOSS et al., U.S. Pat. No. 5,917,899, the disclosure of which is expressly incorporated herein by reference in its entirety, teach a method for providing an interLATA virtual private network, using host or “hub” switches in the PSTN to connect calls within the network. An interLATA, intra-network call is routed, based on instructions from an SCP, from an originating switch to a first hub switch within the same LATA as the originating switch and then to a second hub switch within the same LATA as the called party number. MOSS et al.'s system is limited, though, to accommodating abbreviated dialing for in-network calls across more than one LATA. Also, MADOCH et al., U.S. Pat. No. 5,995,605, the disclosure of which is expressly incorporated herein by reference in its entirety, teach a hub switch that combines calls from multiple switches to a centrex telephone line into a data stream. The data stream is transmitted over a digital trunk to an information network node servicing a high traffic computer network, such as an Internet access system. MADOCH et al.'s system is limited to routing calls to an information network having a predetermined access number and does not handle routine customer telephone traffic.
The overarching need is to have a comprehensive network alternative to private facilities, such as ETN, including centralized administration of carrier and private route selections as well as centralized call screening functions. Moreover, the “virtual network” should be a uniform application. Currently, the virtual network systems do not provide the needed flexibility for efficiently merging a PSTN system and a private network to maximize call flow efficiency and cost control.
Rather, the systems either restrict calls to the PSTN or to private networks with little flexibility, or the systems route calls over a combination of the PSTN and private networks, based on a real time analysis of trunk and carrier availability, often resulting in duplication of effort or overuse of one of the sets of resources. For example, small remote locations within a private network tend to funnel calls, as a practical matter, through the same ETN node. Use of only private trunk groups in this situation is overly expensive because the call traffic from individual locations is insufficient to warrant the expense of the private lines. Use of only the PSTN therefore appears to be more appropriate. However, at some point, the aggregated calls from several remote locations begin to parallel one another to access the single ETN node, thus overusing the PSTN and causing excessive expense to the customer. A private trunk group dedicated to the ETN node in this situation would handle the call traffic less expensively.
Conventional systems also offer limited reporting functions. For example, current systems produce call data records, referred to as station message detail recording (SMDR), which is used by customers to determine outgoing call activity on a station by station basis. SMDR call details are accessible through an optional SMDR port on a PBX where the call originates, or in the case of centrex, through the serving network central office switch where the call originates. With centrex, SMDR records flow to an SMDR host central processing unit in preparation for SMDR delivery to the customer. The centrex SMDR network is known as centrex station message detail recording and transmission (CentrexSMART). The current centrex and PBX SMDR systems, however, are independent of one another so it is not possible for the customer with both PBX and centrex SMDR records to have the data streams combined and delivered to the customer as one aggregated data stream direct from the serving PBX or network switch.
Furthermore, the collection and dissemination of the SMDR data is currently very decentralized. The SMDR data on which the calling records are based are collected at local service switching points. Therefore, each PBX providing SMDR data requires a specific connection to its SMDR port, and in the case of centrex, each network switch must have direct connectivity to the SMDR host (i.e., CentrexSMART) for the data to be transferred. Also, each switch/PBX must be loaded with a relatively expensive SMDR package, for instructions regarding records to capture and transmit. For example, if the customer's network is serviced by five service switching points, the customer or local exchange carrier must have five SMDR packages loaded at all five locations.